The present invention relates to a method for supplying heat to an engine for external heat supply by intermittent combustion, and to an engine for carrying out the method.
A hot-gas engine operates with a closed thermodynamic system in which a working medium, such as hydrogen, helium or air, is supplied with heat from a heater. The heater is supplied with heat externally, for instance by the combustion of fuel in a combustor.
The heat transfer is considerably improved if the combustion is carried out intermittently because the build-up of insulating interfaces in the heater will be obviated by the constantly varying direction and velocity of the combustion gas flow.
Further, it is possible to make the supply of air to the combustor and the discharge of exhaust gases from the combustor occur automatically, whereby there is no need of a fan requiring much energy.
For engines with external heat supply, for instance hot-gas engines, use is normally made of combustors operating with continuous combustion, large heat transfer surfaces and high flow velocities being required for the combustion gases in order to obtain the required heat transfer to the engine. This also gives rise to the need of a powerful fan the energy requirement of which decreases the output of the engine drive shaft to an undesirable extent.
The difficulties of appropriately performing intermittent combustion in engines with external heat supply have entailed that there is today hardly a single practicable method for such purposes.
The object of the present invention is to integrate the function of intermittent combustion in the heater of a hot-gas engine in such a manner that the conditions for heat transfer are satisfied, while maintaining the intermittent combustion.